This invention relates to internal combustion engines and, more particularly, to improvements in their efficiency, including size and weight reduction and equalization of the air-fuel ratio.
Although it is desirable from the point of view of engine efficiency and fuel conservation to maintain a uniform air-fuel ratio in an internal combustion engine over the full range of operating conditions, this is difficult to achieve in practice. In a carbureted engine, fuel is fed to the throat of a venturi through which intake air passes prior to entering the cylinders; the fuel flow rate is determined by the air flow rate through the venturi, which in turn is controlled by a butterfly valve in response to the throttle. In a fuel injuction engine, the fuel is fed directly into the cylinders through injectors; the fuel control rate is controlled by the fuel pressure and/or injection interval in response to sensors of engine parameters, including engine speed.
One common type of internal combustion engine has one or more cylinders each with a pair of opposing pistons, i.e., the pistons alternatively move together and apart during operation. Piston rods extending from the ends of the cylinder are connected by rocker arms to a crankshaft that is driven by the operation of the engine. The same amount of air is always taken in regardless of the engine speed, although less air is required at low speed per cycle. This unnecessarily uses engine power for air compression, thereby leading to inefficiency.